Process of forming nitrogen compounds



W! IVESSES 2. Walk. yflwmw C. B. JACOBS.

PROCESS OF FORMING NITROGEN COMPOUNDS.

APPLICATION FILED AUG. 19, I916.

Patented Oct. 5, 1920.

ozaz/zmzzhm A NOR/VH8 UNITED STATES PATENT OFFICE.

CHARLES B. JACOBS, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR, BY MES'NE .ASSIGN- MENTS, TO AIR REDUCTION COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Oct. 5, 19 20.

Application filed August 19, 1916. Serial No.115,758.

To all whom it may concern:

Be it known that I, CHARLES B. J ACOBS, a citizenof the United States, residin at Bloomfield, in the county of Essex and k tate of New Jersey, have invented certain new and useful Improvements in Processes of Forming Nitrogen Compounds, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to processes for the production of nitrogen compounds, and with respect to its more specific features to a process for the production of alkali metal,

cyanids.

One of the objects of the invention is the provision of a practical process by means of which may be eflected the direct combination of free, or elementary, nitrogen with alkali metal compounds to form cyanids.

Another object of the invention is the provision of an efficient process for the production of J mixture of an alkali metal and carbon in such intimate relation as When treated to facilitate the production of cyanids.

Another object of the invention is the provision of a practical process. for the direct combination of free nitrogen with alkali metal compounds to form cyanids, and which by a slight modification will result in the production of cyanamid.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the several steps and the relation and order of one or more of such steps with relation to each'of-the other-s thereof, which will be exemplified .in the hereinafter disclosed process, and the scope of the application of which will be indicated in the claims that follow.

In the accompanying drawing forming part of this specification, there is shown an apparatus suitable for carrying out the process herein disclosed.

It is well known that the inert chararter of free, or elementary, nitrogen has heretofore prevented its direct combination with other elements, except in meagre traces, without the influence of catalytic agents, or the electric spark,'or silent discharge, or the electric arc. Heretofore to effect combination of nitrogen with the alkali metals to form cyanids or intermediate compounds from which alkali cyanids may be formed, it has been necessary to use some compound of nitrogen which will break up at the reacting. temperature, and furnish nitrogen in a nascent state.

By means of the present process alkali metal compounds may be effectively treated with nitrogen to produce different compounds of nitrogen, and further, metal compounds may be prepared or placed in such chemical or physical condition as will be most suitable for treatment with nitrogen.

While any of the alkali metal compounds may be treated in accordance with the prescnt process so as to produce the related cyanids, as a pratical illustration, the invention is herein disclosed in connection with the production of sodium cyanid from sodium carbonate, this latter furnishing a cheap and readily available compound for the purpose.

The sodium carbonate in a finely pulverized condition is intimately mixed with coking coal, also in a finely pulverized condition, suliicient coal being employed to furnish an excess of carbon over the theoretical ampunt required for carrying out the react ons hereinafter. referred to. This mixture of sodium carbonate and coking coal is placed in a suitable retort provided with an opening in the top for the escape of the volatile products of the coal and other gaseous products of the reactions, and with a second opening in the bottom for the introduction of nitrogen. The retort is heated sufiiciently to expel the volatile elements of the coal, a temperature of 700 degrees C. being found to be sutficient for the purpose. \Vhen allthe volatile matter of the coal has been expelled, there results a porous composition of-coke, sodium carbonate. and some sodium oxid, the oxid resulting from the rereduction of some of the carbonate during the coking operation. or mixture, of the alkali metal compound and carbon contains the sodium compounds trapped within the cell walls of the coke, each. particle of finely divided sodium compound.- being surrounded, as'it Were, by an envelop of porous carbon. Thus the sodium This porous mass,

compound and the carbon are in the most favorable condition for intimate physical contact between the two, and when the nitro-- gen is turned into or associated with such a mixture, the nitrogen as well is brought into intimate contact with the carbon and the compound by reason of the porosity of the mass. Thus the sodium compounds may be said to be prepared in a physical condition facilitating their'change of form and their passage into a nascent state in intimate physical and chemical contact with nitrogen and carbon.

Having obtained the intimate mixture of the alkali metal compound with carbon, as just explained, the temperature of the mixture in the retort is raised and nitrogen is into intimate contact with the sodium com-.

pounds and carbon owing to the porosity of the mixture. The sodium compounds in contact with carbon at the temperature referred to are reduced from carbonate to oxid and pass momentarily into the metallic state, and being thus in a nascent condition in intimate contact with carbon and nitrogen they combine to form sodium cyanid.

The total reaction which takes place by the process above explained may be expressed by thev following eqiiation:

It is believed that the total reaction takes place in three phases, as follows:

It will be seen that phases (2) and (3) take place simultaneously whereas phase (1) may be carried out separately from phases (2) and (3) and in separate retorts in the absence of nitrogen by extending the coking operation in the first step of the process at a higher temperature. The resulting porous mass of sodium oxid and carbon may then be charged into a second retort for the performanceof phases (2) and (3).

It is found that an excess of nitrogen and carbon over that required by the above equations facilitates the process if it is not absolutely essential. An insufficient supply of nitrogen may result in the formation of metallic sodium in phases (2) and While nitrogen may be introduced under normal conditions of pressure, its introduction under an increased pressure, a pressure, say, of from 10 to 15 lbs.' per square inch will, however, be found to increase the velocity of the reaction, and consequently increase the yield of cyanid for a given time. The pressure seems to cause a more rapid penetration and contact of the nitroua o+ac+auzua cu +oo It is to be understood that nitrogen in a free, or elementary, state is employed in phases (2) and (3) of the process, although the association of some other gases with the nitrogen may be permitted provided they are not such as to interfere with the formation of the alkali cyanid. The nitrogen of the air may be employed, and may be separated from the other constituents of the air in any manner which will produce the ni trogen in a condition to be introduced into the retort. .One way of obtaining such nitrogen is by the use of a two cylinder internal combustion engine of the four-cycle type in which gasolene or other fuel is employed. One of the cylinders of the engine is arranged to work as a compressor on the exhaust gases from the other. cylinder. The mixture of fuel and air fed to the-motor cylinder is so regulated that the exhaust gases will be composed of substantially a mixture of nitrogen and carbon dioxid. This mixture is passed directly to a cooler and a set of scrubbers containing glass wool and caustic soda or other compounds whichwill absorb CO for removing carbon particles and carbon dioxid. The cleaned gas now substantially pure nitrogen is passed into the compressorcylinder of the engine and compressed to from 100 to 150 lbs. per

square inch and passed to a gas storage tankfor delivery to the retort as needed. It may be stated that the removal of carbon dioxid in the scrubbers may be dispensed with, and the mixture of nitrogen and carbon dioxidpassed directly into the storage tank. Un-

livered to the furnace as needed through a superheater filled with incandescent coke.

'der such circumstances the mixed gas is def fore described. It is preferable, to perform the first step of the process, that is the coking of the charge so as to obtain the intimate mixture, of alkali metal compound and carbon in a furnace or retort separate from that in which phases (2) and (3) are performed, andto carry the first step of the process sufiiciently far to not only drive off the volatile matter of the coal, but also to work into the first phase of the reactions,

- and to reduce as much of the sodium carbonate to oxid as possible. For this purpose ordinarycoal gas retorts maybe employed.

. in the coal The coking coal used should contain a high percentage of fixed carbon, say from to 78 per cent. and should be as low in mineral matter and sulfur as possible. A charge is made up to contain approximately 60 to 64 per cent. by weight of sodium carbonate, and 40 to 36 per cent. by weight of coking coal. With ahigh volatile matter coal, 3. part of the coal may be replaced by some other form of fixed carbon as, for example, the charge may contain 60 per cent. sodium carbonate, 34 per cent. coking coal, and 6 per cent. charcoal. Emphasis is laid on the fact that the best results are obtained by having all the constituents of the charge in finely pulverized condition and intimately mixed. Such a cha-rge'is then placed g'jas retort and heated. toabout 700 degrees until all of the volatile matter of the coal is expelled and a considerable portion of the sodium carbonate reduced to' oxid. This point is indicated by the diminution of the blue flame of CO produced by the first phase of the reaction, that There is thus obtained an intimate mixture of alkali metal compound and carbon which may be stored in air-tight bins for future association with nitrogen as before explained, or may be transferred directly to the furnace illustrated inthe drawing, in which the numeral .1 indie-ates the drum or oven fall out.

oven thereof. In the embodiment illustrated, the numeral 2 indicates the outer walls of the furnace composed of fire brick, or other material, having a high resistance to fusibility by heat, the drum-1 standing vertically therein spaced from the lateral walls thereof and surrounded by a protective shell of aluminum oxid (A1 0 In the combustion chamber 3 of thefurnace is placed an effective heat radiating substance, such as thermite slag, in position to be heated by a producer gas flame introduced through the burners 4, the latter communieating with a suitable supply of gas, as producer gas. Above and below the furnace the drum 1 is closed by covers 5 and 6 which may be hinged thereto and secured in position by clamps 7 and 8 which latter may be removed to permit the covers 5 and 6 to be moved to uncover the openings. The oven 1 may be charged through an opening closed bya removable plug 9 and the temperature of the mass in the furnace may be indicated by means of a thermo couple 10 connected with a pyrometer 11, the thermo-couple projecting through the cover 5.. The numeral 11' indicates a pressure gage communicating with the interior of the oven, and 12 indicates a pipe communicating with the oven. and carrying a safety valve 13. Communieating with the pipe 12 is a pipe 13 prothe clamp 8 may be removed whereupon the cover 6 will drop and the contents of the The numeral 15 indicates a gas storage tank for the storage of nitrogen, or for a mixture of nitrogen and CO obtained from the combined internal combustion engine and compressor indicated generally by the numeral 16. At 17 and 18 are the scrubbers, the latter being connected to the tank 15 by a'cheekvalve 19. The numeral 20 indicates a reducing valve and meter in the pipe line '21 leading from the storage tank '15 to the oven 1. The intimate mixture of sodium compound and carbon previously referred to is charged into the oven 1 through the openingcovered by the plug 9, and the furnace brought to a temperature of approximately 800 degrees C.. as indicated-by the pyrometer 11. Nitrogen from the tank 15 is then admitted to the charge after passing the reducing valve, and the meter 20, the meter serving to measure the quantity of nitrogen used and the reducing valve serving to obtain the pressure desired. As soon as the nitrogen is turned into the even through the pipe 21 the temperature of the charge .is

950 C. The reactions of phases (2 raised to approximately between 940 and and (3) then begin to take place. The C produced in the reaction is led off at the end of the pipe 13 and serves as an indication of the progress of the reaction. When CO is no longer evolved the reaction is complete. The pressure gage 11' serves to indicate the pressure of nitrogen plus the pressure of the CO evolved by the reaction going on. Ordinarily the relative amount of CO and nitrogen pressure is taken from time to time by closing the nitrogen inlet valve 19' and reading the internal pressure due to the evolution of CO by the reaction: when this is m'l, it shows the end of the reaction. The safety valve for the pipe 12 may be set to release at about 12 lbs. per square inch.

The length of time required to carry out the (2) and (3) phases of the reaction varied somewhat by the character of the coke produced by the different coal, and the reaction may be carried nearly to complet-ionor stopped at some intermediate point when suflicient sodium cyanid for working has been formed. In any case the furnace product will be composed of a mixture of sodium cyanid, sodium oxid. sodium carbonate, and carbon. At the end of the given period the contents of the furnace are dischargedI When the formation of sodium cyanid has been carried to the proper point, the nitrogen is shut off and the inlet pipe 21 disconnected. The clamp 8 is then loosened and the charge allowed to drop into an air tight container for cooling. A new charge is then placed in the furnace, and the-operation of forming sodium cyanid repeated.

After the charge expelled from the furnace has become cold, it is lixiviated with water, the temperature being kept below 30 C. The insoluble carbon residue is filtered off and the solution which contains sodium cyanid, sodium carbonate. and sodium hydrate is evaporated in 'vacuo and the sodium cyanid separated from the carbonate and hydrate by fractional crystallization. The sodium hydrate left in the solution is carbonated and added to the separated carbonate, dried and used for making up subsequent furnace charges.

Thus by the above described processes are accomplished, among others, the objects hereinbefore referred to.

As many changes could be made in carrying out the above process without. departing from the scope of the invention. it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein de scribed and all statements of the scope of the invention, which, as a. matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a process of forming alkali metal cyanid the method of preparing the furnace mixture which comprises, intimately com mingling carbonaceous material and an alkali metal compound in a dry condition, and heating the mixture while in a loose, pulverulent condition to expel the volatile constituents thereof.

In a process of forming alkali metal cyanid, the method of preparing the furnace mixture which comprises, intimately commingling coking coal and an alkali metal compound, and heating the mixture while in a loose, pulverulent condition to expel the volatile constituents and produce a porous coke having the alkali metal com pound trapped within the cell walls thereof.

3. In a process of forming sodium cyanid, the method of preparing the furnace mixture which comprises, intimately commingling coking coal and scdiumcarbonate,

and heating the mixture while in a loose .pulverulent condition to expel the volatile constituten-ts and produce a porous coke having sodium carbonate and oxid trapped within the cell walls thereof. 7

4. A process of forming alkali metal cyanid which comprises, intimately commingling carbonaceous material and an alkali metal compound, heating the mixture while in a loose, pulverulent condition to expel volatile constituents, regulating the temperature to a-gglomerate the mixture without fusing and subsequently introducing nitrogen to the mixture while the latter is maintained at an elevated temperature.

5. A process of forming alkali metal cyanid which comprises, intimately commingling coking coal and an alkali metal compound, heating the mixture while in a loose, pulverulent' condition to expel volatile constituents and produce a coke having the alkali metal compoundtrapped within the cell walls thereof and subsequently introducing nitrogen to the mixture while the latter is maintained at an elevated temperature.

6. A process of forming sodium cyanid which comprises, intimately ,commingling carbonaceous material and sodium carbonate, heating the mixture while in a loose, pulverulent condition to expel volatile constituents, regulating the temperature to agglomerate the mixture without fusing and subsequently introducing nitrogen to the mixture while the latter is maintained at an elevated temperature.

7. A process of forming sodium cyanid which comprises, intimately commingling coking coal and sodium carbonate, heating the. mixture while in a loose, pulverulent condition to expel volatile constituents and to produce a coke having sodium carbonate and oxid trapped within the cell Walls thereof and subsequently introducing nitrogen to the mixture while the latter is maintained at an elevated temperature.

In testimony whereof I affix my signature, in the presence of two witnesses.

CHARLES B. JACOBS.

Witnesses:

J. W. ANDERSON, C. J. KULBERG. 

